ON THE DEVELOPMENT OF THE SPERMATOZOA. 
87 
generating spheroid with very little protoplasm clothing them. 
The nucleus undoubtedly becomes the rod-like head of the earth- 
worm^ s spermatozoon^ and the filament is as undeniably formed 
from non-nuclear protoplasm. The sperm-blastophor of the 
earth-worm is not nucleated, and it atrophies and disappears after 
it has shed its crop of spermatozoa. This must be brought into 
relation with the fact that the development of the spermatoblasts 
proceeds not in the testis itself, but after the spermatospores 
have been shed from the testis and taken into the seminal re- 
servoirs. 
On the other hand, we find in the frog and salamander that what 
corresponds to the blastophor is a mtcleated body (see fig. 7 4). The 
blastophoral nucleus was indeed seen and figured by Kolliker in 
fig. 5 V of his memoir. In the frog and salamander the nucleated 
portion of the blastophor (which in these animals is not central 
but lateral) remains adherent to the loall of the seminal tube or 
crypt, and only a portion of the corpuscle breaks off, carrying 
with it the elongated nuclei, which become heads of spermatozoa. 
Thus, in the frog and salamander, a portion of the sperm-poly- 
plast, the nucleated blastophor, remains every year in the period 
succeeding the breeding season, and is very probably ready to 
resume its activity and produce a new crop of spermatozoa after 
one crop has been cleared away. These nucleated blastophors 
are seen forming the lining of the testicular tubes in the frog. 
On the other hand, the primitive testis cells or spermatospores of 
the earth-worm pass away from the testis into another organ (the 
reservoir) in order to undergo their development ; the whole mass 
of the sperm-cell is. detached from its site before the blastophor 
and spermatoblasts have been differentiated. Hence the central 
position of the blastophor and its temporary, evanescent cha- 
racter. 
There is another kind of corpuscle vrhich occurs in prepara- 
tions of a well-developed seminal vesicle (reservoir) of an 
earth-worm, and for a long time it was a puzzle to connect 
it with any part of the previously described history of a sperm- 
cell, but the final conclusion to which I have arrived is 
that it has no connection with it at all. What the function 
of these cells in the reservoirs is I do not know ; it is 
possible that they form a kind of packing material during the 
growth and development of the spermatozoa, and may be con- 
nected with the nutrition of the developing cells and the periodic 
atrophy of the vascular framework of the reservoir. 
In size these cells vary, but attain in the larger specimens a 
diameter of -s-TToth inch, and may be called, even wlien pale in 
tint ‘Hhe brown corpuscles.^^ They have very generally a brown 
